DOE should focus resources on R&D to advance automated stove technologies

 The Department of Energy Bioenergy Technologies Office (BETO) released a Request for Information (RFI) seeking feedback on defining the goals and objectives for a planned effort to collect in-situ wood heater performance data in the field. The deadline to submit comments was September 30, 2024. John Ackerly, AGH President, submitted the following comment: 

There are a number of small portable
emission testing devices for wood stoves
that can be used in situ, or larger lab
equipment can be moved to a home.

"We believe BETO should minimize its role in funding in-situ testing efforts because in-situ testing is usually very complex and expensive, given BETO’s funding for residential wood heater technology development. There are many distinct objectives and reasons to do in-site testing, and stakeholders could eloquently make the case for any number of them. But given the size of BETO’s budget, we do not feel there is a compelling enough type of in-situ testing that is likely to be undertaken.

BETO’s mandate is to “support the development of cleaner burning, higher efficiency residential wood heaters” and it seems this has been interpreted more broadly over time, which is understandable to some point, given the dearth of high quality applications to develop next generation stove technology.

We would urge BETO to only fund in-site testing to the extent it directly focuses on modern, more automated stove technology. For example, it may be worthwhile doing some in-situ testing with an automated stove side by side with a traditional manually operated one, to provide data about how beneficial automation can be, if at all.

The list of questions in the Four Categories suggest that this RFI is wide-ranging without parameters related to development of cleaner burning, high efficiency residential heaters. In the United States, stoves must be tested for PM 2.5 to be certified for sale. Efficiency, as measured by B415, is not regulated, but tested and an existing IRS tax credit gives an incentive to hit 75% efficiency, HHV. Any new generation of more modern, cleaner and efficient wood stoves will need to focus on these metrics first.

To understand the potential of modern, automated stoves, it may be just as relevant to study pellet stoves, to understand how and why they have such a predictable emissions profile, compared to cordwood stoves. It is also relatively easy to test how clean and efficient pellet stoves are in-situ after 1 to 10 years in operation.

To achieve testing goals of how pellet stoves perform after 1 – 10 years of use, I would recommend simply using a Testo 380 and principally test for PM2.5, enabling more sampling of more devices.

There are a multitude of academic inquiries into residential wood smoke but BETO should first determine what avenues there are to more directly advance an R&D agenda, which could include emissions data showing how automation can reduce emissions. Cordwood furnaces have already made the transition from being manually operated to controlled by sensors, and the evidence is clear that sensors will keep a boiler or furnace far cleaner.

Some stakeholders who are heavily invested in manually operated stoves may want BETO to undertake in-situ testing studies, which can be endless. But one test of this RFI will be whether those stakeholders who are doing R&D on modern, more automated stoves need in situ testing data, and if so, what kind. Similarly, it may be instructive to see what kind of in-situ testing is recommended by stakeholders who regulate wood stoves, or are involved in health related studies.

BETO could consider doing an RFI on how to develop the next generation of wood stoves in the United States. R&D is perhaps the most important avenue but DOE funding in the solar, wind and geothermal sectors address scores of barriers to bringing a renewable technology to scale. Those barriers can also be addressed in the eco-system surrounding the wood heater community. Obviously, the wood heater sector will never have that level of resources, requiring a careful assessment of where scarce resources can best be used.

An RFI that engages this community on how to advance automated stove technology may help better understand why major manufacturers are hesitant or whether there are other initiatives that could be undertaken. In-situ testing may be one of them, but an RFI solely on in-site testing sends a confusing message to the wood heating community unless BETO better explains how it is part of a strategy to develop modern, more automated stove technology.

Comment on Massachusetts's Clean Heat Standard

The Alliance for Green Heat just submitted a comment to Massachusetts's Department of Environmental Protection concerning their Clean Heat Standard (CHS). To learn more about their CHS
check out this useful document. Ultimately, a CHS is a policy tool to require heating energy suppliers to gradually replace fossil heating fuels with cleaner heat over time by implementing clean heat or purchasing credits. Some would like to see the exit of advanced wood heating/automated wood heating from the CHS. The Alliance is in opposition to its removal. Please see our full comment below.

"The Alliance for Green Heat appreciates the opportunity to share comments regarding the Clean Heat Standard. We are a nonprofit that advocates for low- carbon heating strategies across the nation. We have a strong expertise in modern wood heating, heat pumps, and energy audits and weatherization, with a focus on low-to-middle-income households.

We believe that Massachusetts must keep advanced wood heating (AWH) technology in the Clean Heat Standard. AWH typically refers to pellet stoves and boilers at the residential level and can also include wood chips in larger systems. Residential wood stoves are not included in the definition of AWH because they do not have the automation to reduce particulate matter (PM) effectively and consistently. A similar term “automated wood heat” is often used and specifically excludes cordwood.

Advanced wood heating has a significant potential to be a complementary decarbonization technology that can increase electrification adoption for middle- income households and serves as an effective alternative heating source for energy providers to offer to customers.

Pellets for advanced wood heating are available locally in New England and are from sustainable sources, a mix of mostly sawdust from sawmills and wood chips from low grade wood. Many studies have investigated the use of woody biomass for local heating and have largely dismissed concerns that forest resources are being degraded to provide wood pellets. (See list of studies and peer reviewed scientific articles at the end of the comment.)

At the residential level, any state Clean Heat Standard should primarily focus on air source heat pumps – and weatherization services. In states with higher percentages of renewable electricity on their grids, heat pumps offer an excellent low carbon solution. However, there are still many drawbacks with heat pumps, many of which can be alleviated with back-up pellet stoves. High purchase and installation cost is of course one of the biggest issues with heat pumps. Pellet stoves can be installed for under $5,000 and can heat a home up to 2,000 square feet. Back-up wood stoves also provide an excellent source of heat when the grid goes down and gives rural consumers the confidence to switch to heat pumps (but we still do not advocate for including wood stoves as an eligible measure for obligated parties).

Because advanced wood heating systems use a fraction of the electricity that air source heat pumps require, its use in a house can reduce electric grid stress during the winter or reduce use of a back-up home battery. Wood pellet fuel has the added advantage of experiencing more price stability than both fossil fuels and electricity. For middle-income families trying to balance monthly costs, automated wood heating could provide a more consistent and affordable heating bill. Pellet boilers and stoves also have major disadvantages, including requiring far more maintenance and repair than heat pumps and repair technicians are not always easy to find. 

Equity concerns are significant for states designing Clean Heat Standards, and primary or back-up pellet heating is one measure that benefits rural low and middle income families. Giving those households the possibility of buying a more price stable fuel and one with an annual cost lower than air- source heat pumps is important. (Massachusetts Clean Energy Center). Another important measure is to ensure that energy auditors in Massachusetts include full inspections of wood and pellet stoves in energy audits. Old, unsafe polluting wood stoves should be eligible for removal but unless energy auditors are trained to do a safety inspection on them, this rarely happens. 

Pellet heating has a documented track record of delivering fewer CO2 emissions compared to electric baseboard heating, oil, propane, natural gas, and even air-source heat pumps with the current electricity grid (Massachusetts Clean Energy Center). (It is sometimes confused with carbon footprint studies on using pellets to make electricity in Europe, a far high carbon emitting application.) Removing a heating technology from the Clean Heat Standard that consistently performs just as well as other renewable energy and has the added benefits of greater price stability and local sourcing, would be misguided and not science based. In comparison, Vermont’s Clean Heat Standard includes automated wood heating. Vermont enthusiastically included this technology as their experience with the benefits of wood heating and ease of technology adoption has long been understood. 

Again, we thank the Department of Environmental Protection for this public comment opportunity. We hope that the Clean Heat Standard remains open to all viable low-carbon solutions to present the best possible outcome for Massachusetts to meet its clean energy and climate goals.

Further Resources:

Biomass Energy Resource Center. 2019. 2018 Vermont Wood Fuel Supply Study. https://fpr.vermont.gov/sites/fpr/files/Forest_and_Forestry/Wood_Biomass_Energy/Library/2018%20V WFSS%20Final%20Report%20with%20Letter.pdf.

Buchholz, Thomas, John S. Gunn, David S. Saah. 2017. Greenhouse gas emissions of local wood pellet heat from northeastern US forests. https://www.sciencedirect.com/science/article/abs/pii/S0360544217315451.

Biomass Energy Resource Center at VEIC. 2016. Wood Heating in Vermont. https://publicservice.vermont.gov/sites/dps/files/documents/Renewable_Energy/CEDF/Reports/AWH% 20Baseline%20Report%20FINAL.pdf.

Innovative Natural Resource Solutions LLC. 2007. Biomass Availability Analysis—Five Counties of Western Massachusetts. https://archives.lib.state.ma.us/bitstream/handle/2452/392593/ocn945986525.pdf?sequence=1&isAllow ed=y.

Olechnowicz, Casey, et al. 2021. Industry Leaders’ Perceptions of Residential Wood Pellet Technology Diffusion in the Northeastern U.S. https://www.mdpi.com/2071-1050/13/8/4178.

Maine Department of Agriculture, Conservation & Forestry. N.d. Wood Heat Maine. https://www.maine.gov/dacf/mfs/projects/woodheatmaine/index.html.

Renewable Energy Vermont and Biomass Energy Resource Center. 2018. Expanded Use of Advanced Wood Heating in Vermont. http://www.revermont.org/wp-content/uploads/FINAL-2030-Wood-Heat- Road-Map.pdf. "